Improved rotor structures for increasing flux per pole of permanent magnet synchronous motor

Kim, Hae-Joong; Moon, Jae-Won

doi:10.1049/iet-epa.2017.0432

Cited by 14 publications

(9 citation statements)

References 21 publications

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“…The rotor topologies used are the surface mounted PM rotor, capped PM rotor, and spoke PM. While there are many other topologies to choose from and variations on each of them, see e.g., [13][14][15][16]18,19,23,24], the three chosen topologies are all relatively simple. All three topologies allow the PM to be represented as a rectangular block with a well defined height and width, along and across magnetisation, respectively.…”

Section: Geometries and Rotor Topologiesmentioning

confidence: 99%

The Influence of Permanent Magnet Material Properties on Generator Rotor Design

Eklund

Eriksson

2019

Energies

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Due to the price and supply insecurities for rare earth metal-based permanent magnet (PM) materials, a search for new PM materials is ongoing. The properties of a new PM material are not known yet, but a span of likely parameters can be studied. This paper presents an investigation on how the remanence and recoil permeability of a PM material affect its usefulness in a low speed, multi-pole, and PM synchronous generator. Demagnetisation is also considered. The investigation is carried out by constrained optimisation of three different rotor topologies for maximum torque production for different PM material parameters and a fixed PM maximum energy. The rotor topologies used are surface mounted PM rotor, spoke type PM rotor and an interior PM rotor with radially magnetised PMs. The three different rotor topologies have their best performance for different kinds of materials. The spoke type PM rotor is the best at utilising low remanence materials as long as they are sufficiently resistant to demagnetisation. The surface mounted PM rotor works best with very demagnetisation resistant PM materials with a high remanence, while the radial interior PM rotor is preferable for high remanence materials with low demagnetisation resistance.interact with the demagnetisation magnetic flux density curve. Different rotor topologies have been studied previously. In [13], three topologies, similar to those studied here, are compared for use in 4-pole traction motors for trains. Similar topologies are compared for use as an aircraft starter-generator in [14]. Five different topologies, not including the spoke-type rotor, are compared in [15]. Ref. [16] also compares five different topologies, including the spoke-type rotor. Ref.[17] compares machines with Nd-Fe-B, Sm-Co and alnico for surface mounted 4-pole machines. Ref.[18] compares three machine configurations for interior v-shaped magnets for two different materials: the novel material NdFe 12 N x and a conventional Nd-Fe-B magnet. A spoke-type rotor with ferrites is compared to a rotor with surface mounted Nd-Fe-B magnets for a wind power generator in [19,20]. A comparison of demagnetization risk for the same generator types is presented in [21].The aim of this paper is to study how the magnetic properties of PM materials affect the machine design in low-speed radial flux PM generators. To our knowledge, there has not been any previous study combining material properties with rotor design and rotor topology choice. The results from this study could give hints on which property to improve when developing new PM materials as well as on the suitability of a material with certain magnetic properties for different generator topologies.

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Section: Geometries and Rotor Topologiesmentioning

confidence: 99%

The Influence of Permanent Magnet Material Properties on Generator Rotor Design

Eklund

Eriksson

2019

Energies

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“…To focus on the sensitivities of the two machines based on the variations in the airgap lengths, l g , the sensitivity of each machine can be performed by partially differentiating (3) and (4) with respect to l g assuming all variables are independent of airgap length. We obtain the sensitivity S g of each machine as shown in (5) and (6), respectively.…”

Section: Mec Analysis Equationsmentioning

confidence: 99%

“…To achieve higher efficiency, permanent magnet (PM) machines are widely used instead of induction or DC motors [1]- [5]. Specifically, flux-concentrating structures, such as spoke-type PM machines or V-shaped PM machines, are continuously developed [6]- [12] because they can provide higher open-circuit airgap flux (OCAF) when compared to the conventional PM machines.…”

Section: Introductionmentioning

confidence: 99%

Sensitivity Comparison of Open-Circuit Airgap Flux Between Surface-Mounted Permanent Magnet and Spoke-Type Permanent Magnet Machines Considering Manufacturing Tolerances

Jun

Kwon

2019

IEEE Access

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The study compares the sensitivities of open-circuit airgap flux (OCAF) between a surfacemounted permanent magnet (SPM) machine and a spoke-type PM machine based on variations in airgap length including additional airgaps between permanent magnets and rotor core and between segmented stator cores to achieve high quality electric machines. Analytical equations deduced from magnetic equivalent circuits (MECs) are used to directly compare natural-born characteristics of the OCAF of the two machines. First, the MEC of each machine is modeled by considering two additional airgaps between the PMs and rotor core and between the segmented stator cores. Second, the OCAF equation of each machine is derived from the MEC to analyze the effects of the design variables on the OCAF. Subsequently, the partial derivative equation of the OCAF equation with respect to the airgap length is obtained for sensitivity analysis. A comparison of the equations of the two machines indicates that the spoke-type PM machine exhibits inherently higher sensitivity and average value of the OCAF when compared to that of the SPM machine. Finally, the results are validated via a two-dimensional finite element method (FEM) by considering the variations in airgap lengths.

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“…In the equivalent magnetic circuits, the rotor magnetic bridge is usually regarded as a constant flux leakage source [19, 22] or a non‐linear magnetic permeance element [16]. According to this method, the flux leakage of rotor magnetic bridge is of concern and the open‐circuit air‐gap flux density of IPM motors was calculated in [10, 16, 20]. To take into account the slotting effect, a piecewise permeance function considering the geometry and material characteristics of IPM motor was proposed in [23].…”

Section: Introductionmentioning

confidence: 99%

“…Thus, the rapid and accurate prediction of the air-gap magnetic field of IPM motors is quite difficult. Up to now, many efforts have been made in terms of predicting the air-gap magnetic field of IPM motors, and many studies mainly focus on the finiteelement method (FEM), the equivalent magnetic circuit method (MCM) [17][18][19][20] and the 2D model in polar coordinates [21].…”

Section: Introductionmentioning

confidence: 99%

Analytical modelling of air‐gap magnetic field of interior permanent magnet synchronous motors

Zuo

et al. 2020

IET Electric Power Applications

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A general analytical model, which is applied to pre‐estimate the air‐gap magnetic field of interior permanent magnet synchronous motors (IPMSM) under the no‐load and load conditions, is proposed in this study. First, the analytical formulas of both the slotless permanent magnetic field and the armature reaction magnetic field are derived, respectively, by virtue of solving the Laplace field equation in polar coordinates. Then, the complex relative permeance is employed to account for the slotting effect. Subsequently, the proposed analytical model, which can reflect the spatial and temporal distribution characteristics of the air‐gap magnetic field, has been applied in a 4‐pole‐24‐slot IPMSM as an example. Finally, the analytical air‐gap magnetic field with the spatial order and frequency characteristics is validated by the finite‐element result. Additionally, the consistency between the analytical and finite‐element results further indicates that the proposed analytical model is effective.

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Improved rotor structures for increasing flux per pole of permanent magnet synchronous motor

Cited by 14 publications

References 21 publications

The Influence of Permanent Magnet Material Properties on Generator Rotor Design

The Influence of Permanent Magnet Material Properties on Generator Rotor Design

Sensitivity Comparison of Open-Circuit Airgap Flux Between Surface-Mounted Permanent Magnet and Spoke-Type Permanent Magnet Machines Considering Manufacturing Tolerances

Analytical modelling of air‐gap magnetic field of interior permanent magnet synchronous motors

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